Albert Barnes Commentary Romans 15:19

"in the power of signs and wonders, in the power of the Holy Spirit; so that from Jerusalem, and round about even unto Illyricum, I have fully preached the gospel of Christ;" — Romans 15:19 (ASV)

Through mighty signs and wonders. By stupendous and striking miracles. .

Paul here refers, doubtless, to the miracles which he himself had performed. See Acts 19:11-12: And God wrought special miracles by the hands of Paul, etc.

By the power of the Spirit of God. This may either be connected with signs and wonders, and then it will mean that those miracles were performed by the power of the Holy Spirit; or it may constitute a new subject, and refer to the gift of prophecy, the power of speaking other languages. Which is its true meaning cannot, perhaps, be ascertained. The interpretations agree in this, that he traced his success in all things to the aid of the Holy Spirit.

So that from Jerusalem. Jerusalem, as a centre of his work; the centre of all religious operations and preaching under the gospel. This was not the place where Paul began to preach (Galatians 1:17–18), but it was the place where the gospel was first preached, and the apostles began to reckon their success from that as a point. .

And round about. (kai kuklō) In a circle. That is, taking Jerusalem as a centre, he had fully preached round that centre until you come to Illyricum.

Unto Illyricum. Illyricum was a province lying to the northwest of Macedonia, bounded on the north by a part of Italy and Germany, on the east by Macedonia, on the south by the Adriatic, and on the west by Istria. It included the modern regions of Croatia and Dalmatia.

Thus, taking Jerusalem as a centre, Paul preached not only in Damascus and Arabia, but also in Syria, Asia Minor, all of Greece, the Grecian Islands, and in Thessaly and Macedonia. This vast area represented a significant part of the then-known world, all of which had heard the gospel through the labours of one indefatigable man.

There is no express mention in the Acts of Paul's going into Illyricum, nor does the expression imply that he preached the gospel within it, but only unto its borders. It may have been, however, that when in Macedonia, he crossed over into that country. This is made somewhat probable by the fact that Titus is mentioned as having gone into Dalmatia (2 Timothy 4:10), which was a part of Illyricum.

I have fully preached. The word here used means, properly, to fill up (peplērōkenai), to complete, and here is used in the sense of diffusing abroad, or of filling up all that region with the gospel. (Compare 2 Timothy 4:17). It means that he had faithfully diffused the knowledge of the gospel in all that immense country.